The present invention relates generally to electrical signal interconnect assemblies and more particularly to a signal interconnect assembly for routing an electrical signal from a signal output to a signal input of a test and measurement instrument, such as oscilloscope, waveform generator, spectrum analyzers, network analyzers and the like.
Test and measurement instruments, such as oscilloscopes, have one or more input signal connectors for coupling one or more measurement probes to the instrument. Typical input signal connectors include BNC and SMA connectors. These types of connectors couple electrical signals from the measurement probe that acquires the signals from a device under test to circuitry within the instrument.
Measurement testing of optical component and assemblies has become an important requirement for oscilloscopes with the increased use of these devices in the electronics industry. The oscilloscope is provided with an optical-to-electrical (O/E) converter that receives an optical signal from the optical device under test via an optical cable. The O/E converter converts the optical signal to an electrical signal and couples the electrical signal via one of the electrical signal input connectors to the oscilloscope. An important requirement for such an oscilloscope and O/E converter system is the calibration of the oscilloscope-O/E converter combination. That is the O/E converter and the oscilloscope are calibrated as a combined unit to produce an optical reference receiver measurement system having a frequency response that matches a 4th order Bessel-Thompson frequency response. Such an optical reference receiver measurement system is well suited for measuring the characteristics of telecommunication system optical components and assemblies.
A limitation on the above described oscilloscope optical reference receiver system is that the calibration of the system is maintained only with the O/E converter calibrated with the oscilloscope. If the different O/E converter is used with the oscilloscope or the O/E converter is used with a different oscilloscope, the optical signal measurement system provides a normal or average response and not a reference receiver response. Customers who switch O/E converters between oscilloscopes loss the 4th order Bessel-Thompson frequency response of calibrated reference receiver.
One solution to this problem is to build the O/E converter into the oscilloscope and couple the output of the O/E converter directly to input circuitry of one of the channels in the oscilloscope. One drawback to this solution is the loss of one oscilloscope channel that could be used for making other types of measurements. A second solution would be to add a precision, high frequency relay switch prior to the input circuitry of the selected oscilloscope input channel. This allows the channel to be used as a standard signal input as well as providing the input from the O/E converter. A drawback to this solution is that the relay switch would introduce additional loss into the channel and possibly generate anomalies, such as reflections, into the measured signal.
What is needed is an interconnect solution for coupling the output of an internal O/E converter in a measurement instrument, such as an oscilloscope, that does not reduce the number of available input channels to instrument nor increase signal loss in the channel.
Accordingly, the present invention is to an electrical signal interconnect assembly useable as a signal routing adapter with a measurement instrument, such as an oscilloscope, for coupling an output signal from an O/E converter internally disposed within the instrument to an input signal connector on the instrument. The electrical signal interconnect assembly has first and second high speed coaxial interconnects with each coaxial interconnect having a central signal conductor and a surrounding shield conductor. Each of the coaxial interconnects have a male side including a male shield contact mateable with a female side having a shield sleeve defining a chamber including a contact facility having a compliant portion operable to flexibly grip the male shield contact. One of the male and female mating sides of the first coaxial interconnect is selected and floatingly attached to one side of a panel over a first aperture formed in the panel. The panel has a second aperture over which a mechanical alignment facility is attached on the same side of the panel as the first coaxial interconnect. The mechanical alignment facility has coarse and fine mechanical alignment portions with the coarse mechanical alignment portion including a closely mating pocket and body. The pocket has a rim and a floor recessed below the rim such that the rim provides a first angular displacement limit of the body. The fine mechanical alignment portion includes a notch defined in one of the pocket and body and a key closely mating with the notch defined in the other of the pocket and body such that the notch provides a second angular displacement limit of the body. One of the male and female mating sides of the second coaxial interconnect is selected and attached to one of the pocket and body. A coaxial cable having a cental signal conductor and a surrounding shield conductor is attached to the corresponding cental signal conductors and a surrounding shield conductors of the first and second coaxial interconnects on the opposing side of the panel.
The first and second interconnects are preferably blind mating interconnects with the associated mating sides of the first and second coaxial interconnects and one of the pocket and body mounted on an electrical instrument and coupled to circuitry in the instrument. In the preferred embodiment, the female mating sides of the interconnects are connected to the instrument. The electrical signal interconnect assembly further includes a separate electronic data interconnect having a first side connected to the pocket and a second side connected to the body. At least one side of the data interconnect includes compliant contacts operable to contact a corresponding set of contacts on the other side, over a range of depths with which the body is inserted into the pocket. In the preferred embodiment, one side of the data interconnect includes pogo pins contained within the pocket, and the other side includes a fixed contact surface.
A housing is attached to the opposing side of the panel with the housing having a base with depending sidewalls positioned against the opposing side of the panel. The base may include cantilever spring members disposed on the base with each cantilever spring member having a fixed end attached to the base a flexible free end with the free ends defining an aperture. In one embodiment, the cantilever spring members extend above the base in a direction opposite the sidewalls. In a second and preferred embodiment, the base includes an aperture with the cantilever spring members disposed adjacent to the aperture and extending below the base in the same direction as the sidewalls. Preferably, the cantilever spring members are integrally formed with the housing.
The objects, advantages and novel features of the present invention are apparent from the following detailed description when read in conjunction with appended claims and attached drawings.